Famine has spread to a sixth area of Somalia and tens of thousands of people have died as a result of severe food shortages, the United Nations has said.

More than half of Somalia's entire population faces a severe food shortage, and the world body has now officially extended the famine zone.

In Mogadishu, there are now half a million refugees and there are warnings from the UN that the famine could spread to the entire south of the country by the end of the year.

The UN says it needs at least $1bn, but one leading charity says the public is being mislead into believing that money can solve the crisis.

Medicine Sans Frontiere, Doctors Without Borders, wants international aid agencies to admit that reaching some of the worst affected victims of famine may not be possible.

The French-based charity has criticised aid agencies and parts of the media for glossing over the realities of the situation.

The World Food Programme, which is providing most of Somalia's food, says lives can be saved, but admits there are millions of people it cannot reach.

Al Jazeera's Nazanine Moshiri reports from Mogadishu.